The invention relates to an oxidative hair dyeing system and process for producing more equalized coloration of hair along the shaft of the hair from new growth hair to old growth hair. More particularly, the invention relates to an oxidative hair dye system employing at least one primary intermediate and at least one coupler which are oxidized to form a coupled dye product in the hair, which coupler dye product is of greater stability to alkaline hydrogen peroxide solution in less porous virgin hair than in more porous damaged hair such that the intensity of the resulting coloration of the hair is more equalized along the shaft of the hair. The invention further relates to an oxidative hair dyeing system in which the initial coloration on new growth hair is more intense than the coloration on old growth or damaged hair.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
However, the condition and structure of human hair is not identical or regular along the entire length of the hair shaft. There is a wide variance of conditions and structure between virgin or new growth hair and older, non-virgin or damaged hair due to a variety of conditions to which human hair is subject. Human hair is subject to a wide variety of conditions, for example, various chemical and mechanical treatments, such as brushing, combing, shampooing, perming, heat treatments, exposure to the sun and the like. The various chemical and mechanical treatments result in the hair becoming progressively more damaged as exposure to these treatments increase. As such, the oldest growth hair at the tips or ends of the hair shaft will generally exhibit greater damage relative to the new growth hair closest to the scalp. The more damaged hair is more porous than the relatively undamaged new growth hair. As a result, inconsistent coloration of the hair is generally obtained in an oxidative dyeing process due to the variable or irregular uptake of the coloring agents along the length of the hair shaft from the virgin hair to the oldest growth hair. Under normal dyeing conditions both oxidative as well as direct dyes color damaged tips of hair shafts to a more intense color than undamaged hair found at the root of the hair shaft.
There is therefore a need for hair coloring systems, compositions and a process which can provide more equalized hair coloration along the length of the shaft of hair, i.e., which can produce substantially more consistent hair coloration along the entire length of a shaft of hair. There is also a need for such systems, compositions and processes which, in addition to providing more equalized hair coloration along the shaft of hair, also provides hair coloration resistant to fading due to washing, shampooing and exposure to the sun.
The invention provides an oxidative dyeing process for producing more equalized coloration of hair along the length of a shaft of the hair, the process comprising:
providing an oxidative hair coloring system comprising an at least one primary intermediate, at least one coupler, and an alkaline hydrogen peroxide or hydrogen peroxide precursor solution;
contacting the hair with the oxidative hair coloring system for an effective period of time to color the hair; and
rinsing, shampooing and drying the hair;
wherein the at least one primary intermediate and the at least one coupler are oxidized to form a coupled dye product in the hair, and the coupled dye product is of greater stability to alkaline hydrogen peroxide solution in less porous virgin hair than in more porous damaged hair such that the intensity of the resulting coloration of the hair is more equalized along the shaft of the hair.
The invention further provides an oxidative hair coloring system for producing more equalized coloration of a shaft of hair along the length of the hair shaft from less porous virgin hair to more porous damaged hair, the hair coloring system comprising:
at least one primary intermediate;
at least one coupler; and
an alkaline solution of hydrogen peroxide or hydrogen peroxide precursor;
the at least one primary intermediate and the at least one coupler being such as to form an oxidatively coupled dye product in the hair stem by the action of hydrogen peroxide from the alkaline solution, and said oxidatively coupled dye product being characterized by greater stability to alkaline hydrogen peroxide solution in the less porous virgin hair than in the more porous damaged hair such that upon dyeing of hair more equalized intensity of coloration is obtainable along the length of the hair shaft.
The invention also provides an oxidative dyeing process for producing coloration of hair along the length of a shaft of the hair, the process comprising:
providing an oxidative hair coloring system comprising an at least one primary intermediate, at least one coupler, and an alkaline hydrogen peroxide or hydrogen peroxide precursor solution;
contacting the hair with the oxidative hair coloring system for an effective period of time to color the hair; and
rinsing, shampooing and drying the hair;
wherein the at least one primary intermediate and the at least one coupler are oxidized to form a coupled dye product in the hair, and the coupled dye product initially produces more intense coloration in less porous virgin hair than in more porous damaged hair.
The invention provides an oxidation dyeing process for the coloration of hair in which more equalized intensity of coloration of a shaft of the hair is obtained along a length of the shaft of hair from less porous virgin hair to more porous damaged hair, the process comprising dyeing the hair with a hair coloring system comprising a hydrogen peroxide oxidatively coupled dye product of at least one primary intermediate and at least one coupler, wherein the oxidatively coupled dye product formed in the hair shaft has a high reactivity with alkaline hydrogen peroxide such that increasing amounts of said oxidatively coupled dye product is destroyed within the hair as the porosity of the hair increases from less porous virgin hair to more porous damaged hair whereby the resulting intensity of coloration along the shaft of the hair is brought into closer equalization.
The invention further provides an oxidative hair coloring system for the coloration of hair for producing more equalized intensity of coloration of a shaft of the hair along a length of the shaft of the hair from less porous virgin hair to more porous damaged hair, the hair coloring system comprising:
at least one primary intermediate;
at least one coupler; and
an alkaline solution of hydrogen peroxide or hydrogen peroxide precursor;
the at least one primary intermediate and the at least one coupler being such as to form an oxidatively coupled dye product in the hair stem by the action of hydrogen peroxide from the alkaline solution, and said oxidatively coupled dye product being characterized by a high reactivity with alkaline hydrogen peroxide such that increasing amount of said oxidatively coupled dye product is destroyable within the hair as the porosity of the hair increases from less porous virgin hair to more porous damaged hair whereby the hair coloring system can bring the intensity of coloration along the shaft of the hair into closer equalization.
In another aspect, the invention provides an oxidative hair coloring system for the coloration of hair for producing coloration of a shaft of the hair along a length of the shaft of the hair from less porous virgin hair to more porous damaged hair, the hair coloring system comprising:
at least one primary intermediate;
at least one coupler; and
an alkaline solution of hydrogen peroxide or hydrogen peroxide precursor;
the at least one primary intermediate and the at least one coupler being such as to form an oxidatively coupled dye product in the hair stem by the action of hydrogen peroxide from the alkaline solution, and said oxidatively coupled dye product being characterized by a high reactivity with alkaline hydrogen peroxide such that said oxidatively coupled dye initially produces a more intense coloration in less porous virgin hair than the initial coloration produced in more porous damaged hair.
It is believed that more equalized coloration of hair along the shaft of the hair is obtained in accordance with this invention by providing a coupled dye product in the hair shaft that is more readily destroyed by hydrogen peroxide in the more porous, damaged, older hair than it is in the less porous new hair. With the process and hair coloring system of this invention, a stronger, more intense initial coloration is produced on intact new hair than the initial coloration provided on damaged hair by the provision of a coupled dye product in the hair shaft that has a higher reactivity with alkaline hydrogen peroxide or hydrogen peroxide precursor whereby more coupled dye product (color) is destroyed in porous damaged hair than in initial new or virgin hair so that more equalized coloration of the hair results along the shaft of the hair. Thus, the coupled dye product of this invention is regarded as a xe2x80x9croot-seekingxe2x80x9d dye.
In accordance with this invention, oxidative hair dyeing systems, compositions and processes are provided in which the coupler employed is 2-amino-8-hydroxyquinoline. This coupler is employed with one or more suitable primary intermediates that form a root-seeking coupled dye product with the 2-amino-8-hydroxyquinoline to produce a stronger, more intense coloration on new or virgin hair than on older, more porous damaged hair.
As suitable primary intermediates that form such coupled dye product with 2-amino-8-hydroxyquinoline to produce more intense coloration on new hair compared to older damaged hair, there may be mentioned N,N-bis(hydroxyethyl)-p-phenylenediamine and 2-aminophenol. The fact that new hair is more intensely colored than older damaged hair is surprising in itself and is rendered even more surprising by the fact that such a result is not obtained with coupled dye products obtained with closely related 8-hydroxyquinoline compounds.
The hair coloring systems and compositions of this invention will contain the coupler of this invention, alone or in combination with other couplers, in an effective coloring amount, generally in an amount of from about 0.01 to about 2.5 weight percent. The primary intermediate(s) will generally be present in an amount of from about 0.01 to about 3.5 weight percent. The molar ratio of primary intermediate to coupler will generally range from about 5:1 to about 1:5, preferably at an equimolar (1:1) ratio, and be employed in any suitable carrier or vehicle, generally an aqueous or hydroalcoholic solution, preferably an aqueous solution. The carrier or vehicle will generally comprise up to about 40 weight percent.
The hair coloring compositions of this invention may contain one or more cationic, anionic or amphoteric surface active agents, perfumes, antioxidants, sequestering agents, thickening agents, alkalizing or acidifying agents, and other dyeing agents.
Any suitable peroxide providing agent can be employed in the coloring compositions of this invention, particularly hydrogen peroxide (H2O2) or precursors therefor.